A conventional thermal oscillator is described in document U.S. Pat. No. 4,044,558 A.
Document U.S. Pat. No. 7,920,032 B2 shows an oscillator device based on thermal diffusion. The oscillator is adapted for generating an oscillator signal. The oscillator device has at least a first heater, a temperature sensor, signal processing means, and a voltage controlled oscillator. An output of the temperature sensor is connected to an input of the signal processing means; an output of the signal processing means is connected to an input of the voltage controlled oscillator. An output of the voltage controlled oscillator in a first feedback-loop has a first connection to an input of the at least one first heater. The voltage controlled oscillator, in use, is capable of generating an oscillator signal, the oscillator signal being provided as heating drive signal to the at least one first heater over the first connection, and the signal processing means are capable of providing a signal for altering a frequency of the oscillator signal, wherein the signal processing means are arranged to implement the function of a synchronous demodulator.
U.S. Pat. No. 6,518,847 B1 shows an apparatus and a method for a thermal feedback oscillator. The apparatus may be directed to produce an oscillation frequency utilizing a thermal heat transfer characteristics of a semiconductor material. The thermal oscillator includes a heat circuit that is arranged to selectively produce a heat signal in response to the output signal. A reference circuit is arranged to produce a reference signal. A thermal sensor circuit is arranged to produce a sense signal in response to the heat signal and the reference signal. A comparator circuit is arranged to produce the output signal in response to the sense signal such that the output signal oscillates between two signal levels at the oscillation frequency, wherein the oscillation frequency is determined by a time constant associated with the heat transfer characteristics of the semiconductor material.
In reference [1], a thermal transistor is described which is adapted for heat flux switching and modulating. The thermal transistor is an efficient heat control device which can act as a heat switch as well as a heat modulator. In reference [1], one-dimensional and two-dimensional thermal transistors are described. In particular, it is shown how to improve the efficiency of the one dimensional thermal transistor significantly.
In reference [2], the influence of surface roughness on near-field heat transfer between two plates is described. In particular, a surface roughness correction to the near-field heat transfer between two rough bulk materials is discussed by using second-order perturbation theory. The results allow for estimating the impact of surface roughness to the heat transfer between two plates and between a microsphere and a plate, using the Derjaguin approximation. Furthermore, it is shown that the proximity approximation for describing rough surfaces is valid for distances much smaller than the correlation length of the surface roughness even if the heat transfer is dominated by the coupling of surface modes.
Document US 2012/0056504 A1 shows a MEMS based (MEMS; micro-electro-mechanical system) pyroelectric thermal energy harvester. The pyroelectric thermal energy harvester is adapted for generating an electric current. It includes a cantilevered layered pyroelectric capacitor extending between a first surface and a second surface, where the first surface includes a temperature difference from the second surface. The layered pyroelectric capacitor includes a conductive, bimetal top electrode layer, an intermediate pyroelectric dielectric layer and a conductive bottom electrode layer. In addition, a pair of proof masses is affixed at a distal end of the layered pyroelectric capacitor to face the first surface and the second surface, wherein the proof masses oscillate between the first surface and the second surface such that a pyroelectric current is generated in the pyroelectric capacitor due to temperature cycling when the proof masses alternately contact the first surface and the second surface.
Document EP 1,684,414 A1 describes a MEMS oscillator drive. The MEMS oscillator drive includes a device layer and sacrificial layers. The device layer and the sacrificial layers have relative high and low thermal conductivities, resulting in induced radial heat flux from the heat sources. The heat is conducted to the edge of the cantilever, where the sacrificial layer ends. Partial deformation appears to take place at the edge of the sacrificial layer, causing actuation of the released cantilever. This type of driving mechanism appears to occur with a laser heating source of low energy, such as approximately 102 uW, and long periods of sinusoidal excitation, such as approximately 50 to 300 ns. With such types of excitation energies, the driving mechanism appears to be primarily thermal in nature, while acoustic wave related phenomena are minor.
Accordingly, it is an aspect of the present invention to provide an improved thermal oscillator.